adjective

remaining loyal and steadfast.

throughout his career, he remained faithful to the principles of Classical art

loyal,constant,true,devoted,true-blue,true-hearted,unswerving,unwavering,staunch,steadfast,dedicated,committed,trusted,trusty,trustworthy,dependable,reliable,obedient,dutiful

noun

those who are faithful to a particular religion or political party.

a muezzin called the faithful to prayer

believers,communicants,adherents,followers,loyal followers,loyal members,congregation,brethren,flock